System for obtaining a fundus image

ABSTRACT

The present invention is related to a system for obtaining a fundus image, constituted by optical means implemented in an equipment to observe and photograph the image of the wall fundus ( 16 ), comprising a capturing optical means composed by high sensibility digital camera, constituted by an image sensor ( 2 ) and focal optical system ( 3 ), said digital camera being used to register a captured image by an afocal optical system, composed by a capturing lens ( 13 ) and its afocal complement ( 6 ); a lighting optical means provided from a arrangement conformed with optical fiber bundle ( 7 ), ( 8 ), ( 9 ) and ( 10 ), halogen light source ( 23 ) or light emitting diode source (LED); wherein said light beam from the halogen light ( 23 ) or light emitting diodes has an annular form when it pass in the anterior part of eyeball ( 14 ) and focus in the pupil plan ( 15 ); both the means having the optical path partially common over the optical axle ( 1 ) from the optical fibers arrangement ( 7 ), ( 8 ), ( 9 ) and ( 10 ) to the fundus ( 16 ), region in that both the beams are coaxial; in that both the optical means are equipped with light polarizers ( 4 ) and ( 11 ), being integrated with mechanical, electronics and computerized components, and applicative program, which allow control the equipment and its multiple operational configurations, conducing image acquisition and processing, and displaying the results.

FIELD OF THE INVENTION

The present invention refers to a system associated to a deviceapplicable in opthalmology, developed to obtain an image of the retinaand to carry out diagnosis of the fundus.

BACKGROUND TECHNIQUE

Conventional equipments projected to obtain fundus images are mainlybased on a technique widely known and used in opthalmology, whichpredicts the wide and uniform lighting of the fundus wall, followed byfrontal capture of the reflected light in this process. The light beamused for lighting should according to this technique, penetrate in theback portion of the eyeball through its periphery c region, allowingthat the region near to the optical axis be free of intense lighting, inorder to not contaminate with spurious lighting the reflected beam thatreturns bringing the image of the fundus.

In order to achieve these objectives, it was adopted for the lightingbeam, as more appropriate an annular form, since it has a cylindricalsymmetry, so, allowing distribute the light beam on the whole circle ofthe pupil periphery. This annular beam must have its focal positionadjusted in the iris region, which coincides with the pupil plan, andshows in this plan a diameter slightly less than the pupillary opening.However, said beam must also have a elevated divergence from its focalposition, to reach the fundus with a wide and uniform energydistribution.

The lighting beam should have necessarily an elevated intensity, so thata significant quantity of scattered light by the fundus returns throughthe pupillary opening, and be sufficient to sensitive the used camera.This is necessary because the fundus wall has the characteristics of adiffuse irradiator, working better as a scatter surface as alight-reflecting surface. The light reflectivity is a function of thesurface properties, the incidence angle, and light wavelength, beingmore accented in higher wavelengths, near to the red visible limit. So,the fundus wall has a low inherent reflectivity.

This necessary elevated intensity is another good reason that thelighting beam presents a ring form, because the excessive spatialconcentration of the lighting beam energy would affect in a adverse formthe intraocular medium, which it is formed by the cornea, anteriorchamber, iris, lens and pupillary opening. The annular form provides aregular distribution of light energy on the whole extension of theperipheral line of the frontal part of the eye, even that it isconsidered that the line of light ring has a narrow width in its focalposition. This method also allows a more uniform lighting of fundus bythe cylindrical symmetry that the ring form provides. The geometry ofthe construction and the depth of focus should be adjusted in order toobtain the most wide and uniform possible lighting.

The simultaneous capturing of the scattered light by the fundus portionsundergone to this lighting is carried out, still according with thistechnique, with an optical system and a device to register the image. Insome old equipment models the lighting beam has not the ring form, but asimple beam form that reaches the eye in the pupil periphery andprojects the light straightly in a small region of the fundus. This beamhas a small angle in relation to the eye optical axis, whereas thecapturing is generally frontal. In these equipment models the inspectionof fundus is carried out by regions, which increases the examinationdifficulty and increases the risk for the patient due to excessiveintensity of a punctual beam.

The anterior part of the eye and the intraocular medium havedifferentiated structures, in whose interfaces occurs an accentedscattering of incident light, this is the principal reason for which thelighting must pass this region by its periphery and in a beam form asnarrow as possible, to avoid possible scattering in these structures maycontribute with undesirable light stains in the image fundus. Theappearance of reflexes from the peripheral region is reduced because theannular beam reaches the cornea in a remote point of the optical axis,in which the incidence angle away from the normal to the surface makesthat the principal reflection be launched far from of the optical axis,and out of the capturing lens.

The means must have a part of its optical paths in common, due to aninevitable spatial superposition of both beams in the intraocular mediumand in the region immediately in front of the eye, causing that thecapturing lens should capture the light coming from the fundus andfocalize the lighting beam in the pupil plane. The most used solution inorder to combine said optical means, is to put between the capturinglens and the others means components, an oblique mirror having a centralhole, which function is allow the partial sharing of the optical axis byboth optical means, so that the capturing beam passes by the centralhole of the mirror and propagates backwards, while the lighting beamfall on obliquely on the mirror being reflected from that to the eye.

The mirror position is calculated in order to be in the focus of aprimary and real image of the light ring projected by a first opticalset of the lighting means, and also be conjugated to the iris positionby the capturing lens. The image formed in the mirror by the firstoptical set is generally produced by placing two screens shutters in thesame plan, one circular and other with a circular hole, whose diameteris a bit higher than the first one. The first optical set of thelighting means must be used to focus the ring in a position near to themirror plan.

As the lighting should be intense and sufficient to that the reflectedlight by the fundus be above of the threshold sensibility of the imagesensor, and as the intensity of the return beam is less than theintensity of the lighting beam, it is essential remove the reflectionsof the most intense beam. The principal reflections take place in thecornea, in the eye internal interfaces and in the lenses used in commonby the two optical means, because the reflected light may contaminatethe capturing beam, causing stains and brighten points in the image,besides elevating the bottom intensity level of the image.

The basic proceeding adopted to remove the reflections in this model, isthe use of polarizers placed in the lighting and capturing means, inthat the polarizer of the capturing means is orientated perpendicularlyto that placed in the lighting means, that is, the fundus is illuminatedby polarized light and the capturing means receives light only withcrossed polarization. The polarizer of the lighting means is constitutedof an object with an annular form, with dimensions slight bigger thanthe thickness of the ring light, and placed in front of the outlet endof the optical fibers arrangement.

The technique is based on a physical principle that establishes theproperties of light interaction with the material means, and defines theeffects on the light in accordance with the characteristics of thematerial. The materials which surface is polished, or smooth, reflectlight with higher efficiency, because the most part of the bright energyis reflected by an angle equal to the incidence angle, in a so calledsituation of speculate reflection, while materials with rough, orwrinkled surface, reflect light in a diffuse way, scattering theincident radiation in a wide angular band. These phenomena haveconsequences on the polarization of incident light, so that thespeculate surfaces reflect light with polarization almost equal to theincident light, at least for angles near to normal, while the diffusesurfaces not polarizes the incident radiation, reflecting light withrandom polarization.

This physical process establishes a criterion to distinguish the lightoriginating from the fundus from that originated by reflections comingfrom speculate surfaces of the eye and from the optical means, since thecrossed polarizer of the capturing means blocks all light with parallelpolarization to the lighting beam, allowing that only the light withperpendicular, or orthogonal polarization, to the lighting beam, passes.The capturing beam has a considerable fraction of light that passes bythe polarizer, since its polarization has a random distribution, and so,always has a parallel component to the polarizer direction. To reachefficiency the system must be optimized so that the light beams pass themost lenses surfaces in angles near to a normal of the surface, so thatthe polarization phenomenon by reflection does not affect the system,since this phenomenon is characteristic of angles near to Brewster.

There are varied light source used in the construction of lightningmeans, such as incandescent lamps and halogens, which have a widespectral band and relatively high intensity in wavelengths in thevisible band, from infrared and of ultraviolet. Tungsten incandescentlamps are more stable and have more simple operation, while the halogenlamps support better a continuous operation regime. The spectral curveof halogen lamps is shifted for shorter wavelengths in relation toincandescent lamps, presenting a reasonable intensity in the ultravioletband, although this curve vary during the use, its intensity remainsquite stable. The fluorescent light, as the high-pressure xenon, alsohaving a wide spectral band are used in more complex and expensiveequipments. All these lamps present common difficulties, as theexcessive divergence of irradiated light that makes necessarily the useof diaphragms, the low energetic efficiency accompanied by high heatdissipation, and the compulsory placing of filters to cut undesirablewavelengths in determined examinations. The divergence makes difficultthe beam collimation and the efficiency in the capturing of emittedenergy, producing not uniform lighting in the fundus if the opticalmeans is not well corrected. The necessity of illuminating a wide regionin the fundus demands a light source with a relatively big emissionsurface, positioned in the focal point of the lighting means, due toplacing of screens shutters, also big, with the ring form.

The light emitting diodes (LED) and laser diodes also can be usedalternatively as light source, since they present less divergence in thelight emission. But the predominant necessity of wide spectral band andelevated intensity makes difficult the option for these components. Theuse of light emitting diodes (LED) is extremely advantageous as a lowcost option for multiple images acquisition, using the light pulses(flashes) synchronized to the acquisitions, because the others lightsources demands an excessive wait time for the electronic reload.

SUMMARY OF THE INVENTION

With the objective in overcome the above-described drawbacks, its isprovided, according to the present invention, a system to obtain afundus image constituted basically by two different optical means,called lighting means and capturing means, which has coaxial opticalpaths and partially superimposed.

The lighting means has the function in projects in the fundus a lightbeam that will be scattered in all directions by the structures of thefundus wall. While, the capturing means has the function in registersthe retina image and other structures of the fundus wall, capturing areflected light portion that emerges from the pupillary opening. The twomainly optical means which compose this equipment are supported bystructures and mechanical devices, fixed and adjustable, and by electricand electronic circuits, servomechanisms, computer and software, whichare used for controlling the equipment, data acquisition, imagesprocessing and displaying the results.

Said lighting means projects a light beam which cross section has a finering form of light in the pupil passage, but presents divergence fromthis point, reaching fundus with a uniform distribution of energy. Thislight ring must pass the pupil plan with a diameter slightly less thanthe pupillary opening, so that the circle of the ring is adjusted insaid opening with the ring line going through its periphery. The ringfocal position coincides with the pupil plan making the circular line ofthe ring as narrow as possible in this plan.

The capturing means includes an optical set as a Kleperian astronomicaltelescope shaped in the situation of conjugated infinite, characterizingan afocal optical system. This mean is made by a set of capturing lensesplaced immediately in front of the eye to be examined, and a set oflenses that work like its afocal complement. The afocal optical systemtransmits the fundus image to a high sensibility digital camera madewith a focal lens in front of an image sensor, in which the opticalelements of the focal lens are placed in a mechanical adjustable device,which allows optimizing the image focus exactly on the image sensor.Considering that the eye optical elements itself contribute to thecapturing means, the composition of the afocal system with the eye,works exactly like an altered system of an astronomical telescopeassociated to the eye of the observer, with the difference that in thiscase the fundus is not the receiver of the image, but the object to beobserved.

The lighting and capturing optical means follows to known principles inopthalmology, which establishes that there must be a partialsuperposition of lighting and capturing beams, since the opticalelements of the eye contribute to both means. Besides, in order toobtain a uniform lighting of the fundus and a frontal capturing of thereturned image, it is convenient that the optical axis coincide and thecapturing lens be used like a common element to the two main opticalmeans of equipment. All these requisites lead to geometry withcylindrical symmetry for the system set.

Said lighting means also presents a common architecture in theequipments existing in the market. However, it includes an innovationdeveloped for the present invention, the use of a specific opticalfibers geometrical arrangement simplifying its construction andalignment. Said optical fibers arrangement has excellent coupling to thelight source in one end of the fibers, a light emitting object with aring form in another end and an opening for passage of capturing beam bythe center of this ring.

The spurious reflections presents in the image are removed using lightpolarizers, used in the two means. The polarizers placed in thecapturing and lighting means are disposed orthogonal, that is, thepolarizers have crossed directions. This arrangement of the polarizersreduces with great efficiency the light originating from reflections inthe lenses of the optical system and in the interfaces of the eyeitself, like the cornea, and represents another innovation in thisinvention.

The appliance set is supported in a mechanical device suited in a tablewith adjustable height, in order that the equipment can be positioned inthe best situation for examination, there is a support and fixationstructure for the patient head, which allows a quick placing of the eyein examination through a gauntlet that makes possible the movement ofthe equipment set in the horizontal plan and in the vertical direction,besides rotation on the axis that passes vertically by the center of theeye. The optical axis of lighting and capturing beam must be near to theoptical axis of the eye during the examination.

The optical, mechanics, electronic, and computational resources, besidesthe applicable program incorporated to the equipment set allow itsconfiguration in four operational ways and the realization of fourdifferent types of opthalmologic examinations. Through the selection ofoptical filters, with specific passages bands, that can be inserted inthe optical paths of lighting and capturing means, it is possible toenable the equipment for differentiated examinations, with the opticalsystem that allows a complete mapping of fundus with good qualityimages, besides be quickly, easiness and operational comfort.

The device herein proposed, on the contrary of the conventional models,uses a projector made with an optical fibers bundle molded in a singlepiece, which it is placed between the light source and the capturinglens in substitution of the holed mirror, which is expendable in thismodel, since that the optical fibers outlet is adapted in the ring form.Besides the mirror, the set of lenses for the formation of the primaryimage also becomes expendable, since the optical fibers outlet itself isthe object to have its image projected. This formed piece substituteswith advantage the optical systems and screens shutters generally usedin order to project the ring. The other end of this fibers opticalbundle is molded in a terminal with excellent coupling on the lightsource, which increases considerably the efficiency in inserting thelight in the fiber, and the use of the bright energy of the lamp using asimple parabolic mirror system and lenses that focus the light emittedby the halogen lamp to the inlet end of an intermediary optical fiber,which drives the light from the source to the optical fibersarrangement.

The advantage of this system is that the new light emitting object, theoptical fibers ring, has light points with reduced dimensions, smalldivergence and Gaussian angular distribution in the beam intensity,allowing the reduction in the size of the projector, and makes thecollimation and beam focusing more simple, besides provide a more finebeam and with great brightness. The line of light obtained is much morefine, avoiding the use of circular diaphragms in the system, and thepresence of a oblique branch of lighting beam. The simplicity achievedwith this arrangement practically removes any difficulty in the opticalalignment of the system making the equipment compact, reduced, light andwith great impact resistance.

The system emits light in a safe power level and appropriate to eachused wavelength, and with spectral band defined for each type ofexamination, selected through insertion of the respective sets offilters in the optical paths of each mean. These instruments areconfigured to carry out up to four types of different opthalmologicexaminations, and are destined to obtain basically images, which afterprocessed allow to determine the characteristics of the retina, itsblood vessels and many others details of fundus.

The system for obtaining a fundus image, object of the presentinvention, accomplishes to the requisites and concepts presentedpreviously, and add innovations that make easy its implementation andperfect its performance.

DETAILED DESCRIPTION OF THE DRAWINGS

Other objectives, characteristics and advantages of the system forobtaining an fundus image, subject of present invention, will be moreapparent from the detailed description, according the drawings asfollows:

FIG. 1—is a schematic representation of the technique presenting thebasic principles used in the construction of the system;

FIG. 2—Shows a detailed lateral view of lighting means and of the eye inexamination;

FIG. 3—Shows a detailed lateral view of capturing mean and of the eye inexamination;

FIG. 4—Shows details the arrangement in ring form built with opticalfibers;

FIG. 5—Shows details of the ends of optical fibers arrangement, whereoccurs the coupling to the light source and the emission of the beam ina ring form; and

FIG. 6—Shows a lateral view of the system, showing the fixed base, theadjustable tower, the support base of the chin, the table and thegauntlet that allow the adjust of the patient eye.

DETAILED DESCRIPTION OF INVENTION

As showed by figures, where identical numeric references identifyingequivalents parts, the system for obtaining a fundus image, object ofpresent invention is constituted basically by two different opticalmeans, which are typical of a retinograph, and called lighting means andcapturing means. These means are described separately and presentoptical coaxial paths 1, with the superposition in a passage of itsdistances between the fundus 16 and the arrangement outlet end of theoptical fibers 7. The optical means are implemented in a equipment thathas mechanical structures, fixed and adjustable, to support thecomponents, besides electronic circuits, computer and applicableprogram, used for control the equipment, images acquisition, imageprocessing and displaying the results.

The first optical mean has the function to illuminate the fundus with alight beam that, must present two essential characteristics, whereas thefirst characteristic is to pass the frontal part of the eye by itsperipheral region, while the second characteristic is to reach thefundus with a uniform distribution of energy. The requisite that thebeam trajectory is contained exclusively in the peripheral region of thefrontal part of the eye has the objective in avoid the reflection andlight scattering in the intraocular medium, leaving the pupil centralregion free of intense lighting.

The second optical means has function in capturing the image produced inthe lighting process being constituted by two lenses sets and a highsensibility digital camera. These lenses sets form a systemcharacterized like an altered afocal telescope, in that the first set iscalled of capturing lens, or eyepiece, and the second set is constitutedby its lens, working like the afocal complement of the capturing lens.

The FIG. 1 shows the used technique showing a complete scheme of the twomain optical means, and its basic working principles, whereas theelements 7, 8, 9, 10, 11 and 13 correspond to the optical components ofthe principal part of the lighting means, and its optical axis 1. Theelements 14, 15 and 16 represent the eye being deeply illuminated; withthe beam reaching the fundus wall 16, after passes by the frontal partof the eye 14, which includes the cornea, anterior camera, iris, lensand pupillary opening 15. The complete capturing means includes theelements 2, 3, 4, 5, 6, 8 and 13 herein represented by the digitalcamera 2, 3; and by capturing lens, or eyepiece of the mean 13, itsafocal complement, or means lens 6, optical set of filters 5 and lightpolarizer 4, which proceed the image acquisition formed by the lightreflected on the fundus 16. The camera is constituted by a focal lens 3,which registers the image formed on a CCD image sensor type 2. Theoptical axis 1 common in both optical means must be adjusted during themeasure proceeding in order to approximately coincide with the opticalaxis of the eye in examination 14, 15, and 16. Also in the FIG. 1 thereare the distances that define the plans of the pupil 15 and thearrangement outlet end of the optical fibers 7 as conjugated distancesby actuation of the capturing lens 13, when considered as an integrantelement of the lighting means. However, when considered as an integrantelement of the capturing means, the capturing lens 13 collects the lightthat goes out from the pupil 15 and a fundus primary real image 12 isformed between this capturing lens 13 and the passage orifice 8 of thecapturing beam, in a position 12 that can present a small variationdepending on the patient eye diopter 14, 15, 16. Said primary real image12, is focused on the image sensor 2, by the afocal system lens 6together with camera focal lens 3, after the capturing beam passes theorifice 8 of the optical fibers arrangement 7, 8, 9, 10. It should beobserved that the eye optical element 14 acts together with thecapturing lens 13 in the formation of the primary real image 12.

In the FIG. 2 it is shown in details, the complete lighting means in alateral view, whereas the used technique in this means is shown up, inthat an annular light beam is produced to penetrate the eyeball 14, 15,16 through the periphery of the eye anterior part 14 and illuminatesuniformly the whole extension of the fundus 16.

The called optical fibers arrangement is obtained from a piece 7, 8, 9,10 made with a bundle of optical fibers 9 shaped in a curved geometricalform and lengthened, been like a pipe, which ends 7 and 10 are fixed bysteel rings, in order to obtain the coupling of the light source at theend 10, a light emitting object with ring form at the end 7 and anopening 8 for the passage of the capturing beam by the centre of thisring. The annular beam is projected from the fibers outlet end 7 passingthe light polarizer 11, also in a ring form, in order to not obstructingthe orifice 8, whereas the capturing beam passes.

The light source used in this specific projector is a halogen lamp 23coupled to the entry end 21 of an intermediary optical fibers bundle 19,20, 21 associated to a concave mirror 22, which has the function infocusing the maximum possible amount of light emitted by the lamp in theentry of the fibers bundle, considering the diameter of these fibers andits numerical opening.

The intermediary optical fibers bundle 19, 20, 21, has the outlet end 19coupled to a entry end of the optical fibers arrangement 10, with theset of condensing lenses 18, whose function is focuses the light emittedby the intermediary bundle in the entry of fibers arrangement bycoupling its respective numerical openings and diameters. Said halogensource 23, emits light in a wide specter of wavelengths, including theultraviolet band, all near the visible and near infrared, opticalfilters are used to blockade the ultraviolet band.

The intermediary couplings between the halogen lamp 23 and the entry end10 of optical fibers arrangement 9 were designed in order to maximizethe light entry in the said optical fibers 9 and homogenize thedistribution of light along the line of the ring formed in the opticalfibers outlet end 7. The optical filters set 17 of the lighting means ispositioned immediately before the optical fibers arrangement 7, 8, 9,and 10. It is possible through mechanical adjusts set the focaldistances and placing the couplings ends between the optical fibersbundles 9, 20, in order to allow the maximum insertion of energy in thefibers.

Alternatively, it can be used as a light source, a set of light emittingdiodes (LED) covering a wide band, which would allow the midriatic use,in that the fundus is illuminated by a set of infrared LED's. In orderto obtain a colorful fundus image or “Red Free”, with visible radiation,the LED is blinked quickly, offering more comfort to a patient.

Said means projects an annular light beam relatively intense, whencompared with the quantity of light that returns reflected by the fundus16, in the same optical path 1, which represents a small fraction of theintensity of the lighting beam. The beam has the form of an extremelyfine ring in its passage by the pupil 15, with a diameter slightly lessthan the pupillary opening and approximately concentric to the opticalaxis of the eye. As observed in the FIG. 2, in a lateral view, thislight beam been emitted peripherical in the outlet end 7 of the opticalfibers arrangement, reaching the capturing lens 13, being focused in thecircle that defines the periphery of the pupil 15, and diverging fromthat, in order to illuminating uniformly the fundus 16.

The FIG. 3 shows in details a lateral view of the complete capturingmeans formed by elements 2, 3, 4, 5, 6 and 13, that should capture andregister a good quality image of fundus 16.

The capturing lens 13 is placed against the eye in examination 14, 15,16, and should receive the whole light that passes by the pupillaryopening 15 bringing back from the fundus 16, subtended by an angle lessthan 22.5° of semi-opening, while the afocal lens 6, projects in frontthe afocal beam produced. The capturing lens 13 must be positioned quitenear and in front of the eye 14, 15, 16, so it is necessary that saidcapturing lens 13, be a common component to the two optical means, andthat combines the two beams in a unique optical path whose axis 1coinciding. The most appropriate construction to become the beams becoaxial, is that the capturing beam passes by the ring orifice 8 formedby the optical fibers arrangement 7, 8, 9, 10 proposed in thistechnique. The functional project of the capturing lens 13 and ofcentral orifice 8 of the optical fibers arrangement must be satisfactoryto the requisites of these two means simultaneously. The digital camera2, 3 that also composes the capturing means is constituted by a set oflenses that form the camera focal lens 3, which project the fundus image16 on a sensor 2 made with a matrix of photosensitive elements. In thecapturing means, the set of optical filters 5 and the light polarizer 4are strategically positioned between the afocal system 6 and 13 and thecamera focal lens 3, because in this region the rays of the capturingbeam are parallel having just surfaced the afocal system.

The focusing lens set 3 of the image, placed in front of the imagesensor 2, as well as the lens 6 of the afocal system, do not interferein the performance of the lighting means since they are not in the sameoptical path.

The system magnification is maintained fixed by the self-characteristicsof the afocal system 6, 13, whose lenses are maintained rigidly in itspositions, in that important bonds of the system are not altered.However, the focuses adjust in the focal lens of camera 3 produces asmall alteration in the magnification.

The FIG. 4 a shows an inferior view of the optical fibers geometricalarrangement 7, 8, 9, 10.

The FIG. 4 b shows a frontal view of the optical fibers geometricalarrangement 7, 8, 9, 10 and an opening e in the optical fibers bundle,

The FIG. 4 c shows a lateral view of the optical fibers geometricalarrangement 7, 8, 9, 10 and an opening e in the optical fibers bundle,

The FIG. 4 d shows a superior view of the optical fibers geometricalarrangement 7, 8, 9, 10.

The fibers of the bundle, in the figures above mentioned, are configuredin a geometrical curved and lengthened form, producing a piece 9 that islikened to a pipe, where in the outlet end 7, or superior, the fibersare positioned side by side, forming a fine and circular line, while inanother extremity of the piece 10, or inferior, the fibers areaccumulated on an intense light source. The optical fibers arrangementhas an optimized geometry to capture the maximum of light in its entryend 10 and conformed to produce a light ring in its outlet 7, by placingof the fibers side by side, in a circular line with diameter of 7millimeters and with a line width from 50 to 200 microns, since they areformed by fibers of this diameter.

The FIG. 5 a, shows the frontal view of the outlet end, of the opticalfibers arrangement, with an opening e of optical fibers bundle, detailsof the endings of the fibers bundles, in that the outlet end of thebundle with the fibers aligned side by side form a ring.

The FIG. 5 b, shows a frontal view of the entry end, in that the bundleend entry with the fibers is accumulated around a point.

The FIG. 6 shows a lateral crossed view of the system integrated andmounted on its compartment.

The system has a fixed base of sustenance from which it is possible toadjust the body of the system with the projection and capturing means.These means are mounted in a sliding base in the body of the system, inthe horizontal plan when in images acquisition operation.

The system can be configured in four operational ways that carry outfour types different of opthalmologic examinations, increasing itsapplicability. The selection of the spectral band of work is effectuatedby a specific combination of optical filters in accordance with the typeof examination to be carried out. The optical means of lighting andcapturing were optimized to correct aberrations, mainly the chromaticaberration in the band between the blue and the infrared, between 400and 950 nanometers, due to four types of examinations that will beeffectuated. Which are: examination with normal colorful image, alsocalled colorful retinography or “color”, where light polarizers are usedand a combination of optical filters which allow lighting and capturingin the whole range of the visible; examination with absence of redlight, called aneritry retinography or “red free”, also with the use oflight polarizers and combination of optical filters which promotelighting with green light and capturing in the whole range of thevisible; examination called fluorescein angiography, in that is used theproperty of fluorescence of this substance, which injected in the bloodcurrent makes possible an accented contrast of the image obtained inexamination of the superficial blood vessels fundus, when filters areused for projection of blue light and capturing of light in thegreen-yellow band; and examination in the infrared band, so-calledindocianine green (ICG), where the property of fluorescence is used inthe infrared band of this substance, which injected in the blood currentmakes possible a contrast accented in examination of the deep bloodvessel fundus, when filters are used for projection and capturing ofinfrared light, respectively in different bands of wavelength, in thatthis examination allows a deep examination of the choroids since theretina is semitransparent to the infrared.

The Program that controls the acquisition and processing of images,besides displaying results obtained from the images, also was developedfor the scheme of operational compatible mode with the configurationsdescribed above. This program (software) allows, from each digital imageproduced and its processing, obtain points to outline the profile ofanomalies present in the retina and in the structures of the wallfundus, resulting in the determination of its form and dimension,including dimensional measures for diagnosis. The equipment handling hastotal operational comfort because it is portable and suitable to beplaced where it will be more convenient for the execution of the work.The appropriate adjust to the patient eye is carried out through agauntlet.

1. A system for obtaining a fundus image, comprising optical meansimplemented in an equipment to observe and photograph the image of thewall fundus, the optical means comprising: a capturing optical meanscomprising a digital camera to register a captured image by an afocaloptical system, the afocal optical system comprising a capturing lensand its afocal complement; a lighting optical means comprising anarrangement of optical fiber bundles, and a light source; wherein saidlight beam from the light source has an annular form when it passes inthe anterior part of an eyeball and focuses in the pupil plane; bothmeans having a partially common optical path over the optical axle fromthe optical fibers arrangement to the fundus region, such that bothbeams are coaxial; and both optical means equipped with light polarizersintegrated with mechanical, electronic and computerized components, andone or more programs.
 2. The system for obtaining a fundus image,according to claim 1, wherein the light source is focused by acollimator in the inlet end of a optical fiber intermediary bundle to befocused by a set of condenser lens from the outlet end of the opticalfibers intermediary bundle passing through an optical filter to theinlet end of the optical fibers arrangement, which drives and emits alight beam in a ring form in its outlet end, the light beam beingprojected in the fundus through the capturing lens.
 3. The system forobtaining a fundus image, according to claim 1, wherein the capturingoptical means and the optical elements of the eye itself form theequivalent of an inverted afocal telescope, and capture the fundus imageto form a primary real image in a position between the capturing lensset and its afocal complement, and before the central hole position inthe optical fibers arrangement, producing an afocal beam to beregistered by the digital camera, with longitudinal mechanical adjust tocompensate for patient eye diopter variation, after the beam passes thelight polarizer and an optical filter.
 4. The system for obtaining afundus image, according to claim 1, the lighting means furthercomprising a geometrical arrangement of optical fiber bundles, thegeometrical arrangement shaped in a ring in its outlet end, and forminga circle in its inlet end, such that the arrangement has a curvedpipe-like profile, and a coaxial hole to the emitting ring in the outletarrangement and to the optical axle of the system, used as a capturingbundle passage.
 5. The system for obtaining a fundus image, according toclaim 1, wherein the orientation of a first polarizer element of thelighting optical means has orthogonal orientation to a second polarizerelement, and wherein the first polarizer element linearly polarizes thelight beam emitted with random polarization in the outlet end of theoptical fibers arrangement, and the second polarizer element filters thelight with polarization component perpendicular to the orientationobtained by the first polarizer element.
 6. The system for obtaining afundus image, according to claim 1, wherein the capturing lensconjugates the object distance of arrangement outlet end of opticalfibers and the image distance of pupillary opening, with respect to thelighting means, and captures an image of fundus forming a primary realimage in a position between the capturing lens itself and the centralhole of arrangement of optical fibers, with respect to the capturingmeans.
 7. The system for obtaining a fundus image, according to claim 1,and further configured to receive four operational modes, and therebycarry out four types of different ophthalmologic examination, having inthe lighting means a light source with wide spectral band, coveringinfrared light and visible bands, and having in the optical path of bothmeans interchangeable light filters, which may be combined to allow auser to carry out four types of examination with the same equipment, theexamination selected from the group consisting of colorful retinography,aneritry retinography, fluorescein angiography and indocianine green. 8.The system for obtaining a fundus image, according to claim 1, furthercomprising a mechanical adjust for longitudinal movement of lensesforming a focal lens of the capturing camera, that enable optimizationof the image focus of fundus on an image sensor, and compensate fordiopter variation of the system.